1. Field of the Invention
The present invention relates to a semiconductor device including an oxide semiconductor and a method for manufacturing the semiconductor device.
One embodiment of the present invention relates to a semiconductor device including a transistor or a semiconductor device including a circuit including the transistor. For example, one embodiment of the present invention relates to a semiconductor device including a transistor in which an oxide semiconductor is used for a channel formation region or a semiconductor device including a circuit that is formed with the use of such a transistor. For example, the present invention relates to an electronic device that includes, as a component, an LSI, a CPU, a power device mounted in a power circuit, a semiconductor integrated circuit including a memory, a thyristor, a converter, an image sensor, or the like, an electro-optical device typified by a liquid crystal display panel, or a light-emitting display device including a light-emitting element.
Note that in this specification, a semiconductor device refers to any device that can function by utilizing semiconductor characteristics, and an electro-optical device, a semiconductor circuit, and an electronic device are all included in the category of semiconductor devices.
2. Description of the Related Art
A technique by which transistors are formed using semiconductor thin films formed over a substrate having an insulating surface has been attracting attention. The transistor is applied to a wide range of electronic devices such as an integrated circuit (IC) or an image display device (also simply referred to as a display device). A silicon-based semiconductor material is widely known as a material for a semiconductor thin film applicable to a transistor. As another material, an oxide semiconductor has been attracting attention.
For example, a technique by which a transistor is formed using zinc oxide or an In—Ga—Zn-based oxide semiconductor as an oxide semiconductor is disclosed (see Patent Document 1).
Patent Document 2 discloses a technique for forming, in an oxide semiconductor film, low-resistance regions that contain a metal element introduced by heat treatment performed with the oxide semiconductor film in contact with a film containing the metal element and contain a dopant introduced by an implantation method through the film containing the metal element.